Bearing and lubricant tester



Dec. 30, 1952 R. J. 5. PIGOTT BEARING AND LUBRICANT TESTER Filed July 5,1951 ms FST'IORNEY Dec. 30, 1952 R. J. s. PIGOTT 2,623,384

BEARING AND LUBRICANT TESTER Filed July 5, 1951 4 Sheets-Sheet 2 ill"!ill INVENTOR. J. 5. EPIGOT'I l. a I j Dec. 30, 1952 R. J. 5 PIGOTTBEARING AND LUBRICANT TESTER 4 Sheets-Sheet 5 Filed July 5, 1951 IN V ENTOR.

HIS ATT RNEY Dec. 30, 1952 R. J. 5. PIGOTT BEARING AND LUBRICANT TESTER4 Sheets-Sheet 4 Filed July 5, 1951 asausn 11mm We 05mm RAPH INVENTOR.R. J. S. PIGO'IT :HIS ATTORNEY Patented Dec. 30, 1952 BEARING ANDLUBRICANT TESTER Reginald I. s. a"... rimbumi, 1a., amino:

Gui! Research & Development Company, Pittsburgh, Pa., a corporation ofDelaware Application July 5, 1051, Serial No. 235,140

1 This invention relates to the testing of bearings having complex loadcycles such as those encountered in operation of an internal combustionengine, the invention being designed primarily for the testing oflubricants under simulated load conditions of reciprocating engineoperation.

In reciprocating engines the connecting rod and main bearings aresubjected to loads which vary both in magnitude and direction. The forcecomponents which result in the loads which must be sustained by thebearings. oi these engines are: first the gas force due to cylinderpressure; second, the inertia force due to the linear acceleration of areciprocating mass; and third, the inertia force due to the'centripetalacceleration ofan unbalanced rotating mass. Although there is somedifference in their application, it is obvious that all internalcombustion engine bearings are subjected to a combination of gaspressures and forces of inertia. Consequently, any iniormation desiredrelative to the lubricant and bearing in the. engine must be obtainedfrom bearings and lubricants used under similar load conditions. Someieatur'es of bearing behavior can be determined fairly well by smallscale tests; but after the undesirable bearings have been eliminated thepromising ones must be observed in the type of service planned. Atpresent, most bearing testing and lubricant testing machines operateunder a load that is constant in magnitude and direction. Hence, ifinformation is required, such as the life expectaxicy of a bearing,effector changes in bearing-design," test bearing materials or lubricantperformance in a dynamic loaded hearing, such information can beobtained only under operating conditions. Therefore, in any bearingtester or lubricant testing apparatus the problem is how to reproducethe precise conditions of service in a convenient and inexpensivemanner.

As will beexplained later in greater detail the essence of thisinvention is that a rotating load of varying magnitude on a bearing canbe simulated by applying pressure oscillations to at least three pointsequidistant around the circumference of said test bearing, and varyingthe magnitude and phase of said oscillations 'in relations to arevolving shaft within said test bearing.

.It is, therefore, an object of this invention to simulate moreaccurately the loads produced on hearings by internal combustionengines.

Another object of the present invention is to provide a simulacrurriof-any bearing load sys tem ina machine whether undirectional, oscil-'laing, pulsating, or Varying rapidlythroughout mecca of rotation.

clearly understood.

a Claims. (CI. 73-10) I A further object of this invention is theprovision of a bearing and lubricant tester which will produce any typeof load including a rotating load such as occurs in an internalcombustion engine and provide for testing of a. lubricant amongdiil'erent bearing designs or testing of many lubricants in a particularbearing design.

These and other objects are accomplished by the provision of the presentbearing testing and lubricant testing machine.

While all testing machines designed for these objectives must-produce aforce or load between the bearing and shaft, a varying loadtestingmachine must not only produce a force or load between the journal andbearing but also relative variation between load direction and loadmagnitude around'the circumference of the hearing. In thepresent'invention these two essentials are produced by at least threeload-applying or pressure-applying units located equidlstantly aroundthe circumference 01' a test bearing holder which supports a testbearing within which a shaft is revolving. The, load oscillations of thepressure applying unit and their resultant force are in a phaserelationship with the shaft rotation. Means are provided for varying themagnitude of the oscillating force's.

From a consideration or the accompanying drawings the bearing testingand lubricant test-- ing machine of the present invention will be moreIn the accompanying Figure 1 is a schematic layout of the testingmachine comprising pressure-producing units. loadapplymg units, and apressure-transmission system connecting them.

Figure 2 is an end view showing the pressuretransmission system indetail.

Figure 3 is a transverse quarter section through one load-applying unit.

Figure 4 is a longitudinal section 0!. the load assembly 2' shown inFigure 3.

Figure 5 is a top view, in part, showinghow the shaft and oscillator aregeared together.

Figures 6 and 7 show the mechanism for measuring force. 1

Figure 8 is a sectional view along line 8-8 of Figure 6.

Referring first to Figure 1, the loading of the bearing is accomplishedby means of at least three, preferably four, load-applying units I lo-,cated equidistantly around circumference of the load ring assembly 2. Ahydraulic load or pressure-transmitting line 3, containing any hydrau-.lic.fluid such as oil, etc., connects load-applying unit I with arespective hydraulic pressure-producing cylinder 4 Within-eachpressuresince only one motor is used for driving all of the cams eachhydraulic pressure-producing cylinder 4 is part of a singlepressure-producing unit. A screw plunger 8 operating in a cylinder 8aprovides a means of altering the volume of fluid in eachload-transmitting line 3, thereby varying the degree of fluidcompression of that load line system. A second pressure producingcylinder 8b that may alternately be combined with cylinder 8a or be aseparate cylinder provides for a momentary and cyclic increase of thebase pressure in the load line system independent of the remaining loadcells and overriding the base pressure communicated to the separate loadtransmitting lines 3 from the common reservoir HI. Each of thesecylinders 8b has a reciprocating piston which is mechanically operatedby a cam, the several cams being mounted on the same drive shaft as cams0 or on another shaftgeared to it or coupled to it in any suitablemanner. The pressure-producing cylinders 8b are designed to be operatedselectively, individually or in multiple by means of variation of camproflle or by mechanical lockout of the inoperative cylinder in anyknown manner. Connected to the system through the check valves 9 is thereservoir l0 maintained at a selected base pressure to supply make-upfluid and prevent air from entering the system.

It is noted that there are at least three loadapplying units l and anequal number of pressure-producing cylinders 4. A pressure-producingcylinder is connected to a load-applying unit through a separatehydraulic load-transmitting line I.

By referring to Figure 2 it can be more easily understood how theselected base pressure is maintained and how the degree of fluidcompression of the system is varied. Figure 2 shows in greater detailthe pressure-producing unit, load or pressure-transmitting line 3,variable volume producing cylinder 8a, auxiliary pressure producingcylinder 8b and reservoir l0. Each of the auxiliary pressure producingcylinders is cam driven, with the driving cams mechanically coupled tothe main pressure producing cylinder cam. The entire system can beoper'ated at any selected base pressure which can be ascertained frompressure gauge It. In this instance this pressure is maintained by gearpump I2 and pressure relief valve 13 which are connected to a manifoldl4 bylines l5 and It. By the use of manifold ll only one fluid supplypump l2 need be used, since each load-transmitting line 3 is connectedto said manifold M through a check valve 9, but an overriding pressureimpulse may betransmitted in any line 3 by operation of one or more ofthe pressure producing cylinders 811. For the sake of simplicity onlyone load-transmitting line Ihas been shown in Figure 2 instead of fourand cylinders 8b are schematically shown. As mentioned in connectionwith Figure 1 each hydraulic pressure-transmitting line 2 connects aload-apply unit I to a respective hydraulic pressure-producing cylinderl which is part of a single pressure-producing unit, shown in Figure 2as a four cylinder oscillator. Figure 2 shows pressure-producing pistons5 being driven by motor I through earns 4 I, which are all mounted onthe same shaft. The degree of fluid compression can be varied bychanging cam proiiies or by altering the volume of fluid in line 2 bysome means such as screw plunger 8 operating in cylinder Is. Aspreviously noted there are three otherlines 2 not shown in Figure 2which connect to the several pressure-producing units from manifold l4,and to each respective load-applying unit I.

Referring-now to Figure 3 one load-applying unit I and the load ringassembly 2 are shown. Each load-applying unit includes a load-applyingpiston I! and. a load-imparting pin ll. Each load-applying piston I1 isoscillated by the fluid in its respective hydraulic load-transmittingline 3, loss of fluid being prevented by a ring gasket l9. There are twovents, not shown in the drawings, in each load cell cylinder to permitescape of air when filling the system. These vents are located on adiameter in the outer circumference of unit i and lead to the fluidchamber. Loadapplying piston I1 is positioned to oscillate againstload-imparting pin it which in turn oscillates against load-impartingring 20 substantially in radial direction. During operation, however,when there is a strain upon load ring 20, there may be a forcetending'to move the loads imparting pin away from the radial direction.To compensate for this tendency the stem of loadapplying piston andload-imparting pin may consist of two elements connected by means of aself aligning ball Joint, or the pin may have a ball in a cavity at itsendas shown in Figure 6. Thus, the pressure transmitted to the piston isapplied by the piston stem to load-imparting pin l8, and by theload-imparting pin to the load ring assembly 2 with which it is incontact.

Referring again to Figure 3, load ring assembly 2 is shown ingreaterdetail. Its essential elements for producing a rotating and pulsatingload are a rotatable shaft 2| mounted to revolve with- I in the innersurface of a split or solid test bearing 22, a test bearing holder 23for split or solid bearings around the outside surface of thetestbearing, andthe load-imparting ring 20. Other elements are usuallyused. particularly since certain measurements are necessary insimulating. bearing loads. For example, I prefer to use a important in abearing tester, means must be pro-. vided to indicate the bearingfriction force. "Eventhough the test bearing is lubricated through oilinlet 25, the test bearing 22, along with thetest bearing holder 23,will tend to rotate in the tion the shaft is turning. In order tomeasure this friction" drag accurately by some device such as a brakearm, an anti-friction bearing must inserted betygeen test bearing holder23 and lost! ring 20. Its inclusion should not distort the imposedforce" pattern on the test hearing. In the embodiment fshown, thisanti-friction bearilig consists ofjan inner race 26 fitting around theoutside off-test bearing holder 23, and an outer race 21 within and incontact with load-imparting ring 20. There are needle rollers 28 betweeninner and outer race rings. It is to be noted that the outer race 21 mayfunction also as the loadimparting ring permitting the load-impartingring 20 to be omitted when the outer race 21 is made suflicientlystrong. The test bearing holder 23, as shown in Figure 4, also serves asa torque arm support since torque arm 29 which is used I to measuretorque as described hereinafter is rigidly connected thereto.

By referring to the various figures the operation of this device forstimulating rotating and pulsating loads on bearings can be readilyunderstood. During operation, as can be seen from Figures 1 and 2. motorI. through cams I, actuates pressure-producing pistons which, byoscillating. compress intermittently the fluid in each hydraulicpressure-transmitting line i. A momentary and cyclic increase of basepressure in any one or more of the lines 3, independent of the others,may be achieved by cam operation of the additional pressure producingcylinders lb. The compression of the fluid in each pressuretransmittingline in turn causes each load-apply ing piston ll to oscillate. Theactual movement of any one load-applying unit is no more than i a fewthousandths of an inch; so there is no appreciable work done in thisoperation. Since the load-applying piston ll, the load-imparting pin itand the load-imparting ring are all in close contact, as is clear fromFigure 3, at any base pressure level, there will be an oscillating forceacting against the load ring, and with an assembly as shown the forcewill be applied at three or more points equidistant around thecircumference of said load ring. By varying the magnitude of this force,and by time-phasing the oscillations with the speed of the rotatingshaft. a rotating and pulsating bearing load can be simulated. The loadmay be in any direction, or the load may be a reciprocating bearing loadrela-' tive to shaft rotation.

It was stressed that the magnitude of the force is varied, and theoscillations are synchronized with the speed of the revolving shaft. Themagnitude of the force can be varied either by varying the volume of theload-transmitting system by manipulation of screw plunger 8 or byvarying cam profiles. The oscillations can be synchronized with thespeed of the shaft by means of soaring, as shown in Figure 5. Figure 5is a partial top view of the bearing tester disclosed herein. showinghow the shaft 2i and the pressure-producing unit are geared together.The cafms i through which the pressure-producing pistons are actuatedare mounted on a common shaft which is geared to shaft II at throughsuitable couplings 3| and. The motor could be attached to the cam shaftas indicated disgrammatically in Figure 1, or an extension of shaftjithrough the gear box 30 may be provided for drive through coupling 33.

Since the force acting on the load ring can be determined by means wellknown to those skilled in the art, a force pattern can be easilyduplicated. Torque can also be readily determined. One system formeasuring force is disclosed in Figures 6 and 8. Two active resistancestrain gauges 34 can be attached to each side of each load-imparting pinI8, and are connected in series at 3i as shown in Figure 6. Magneticstrain gauges could, instead, be used and attached to each of theload-imparting pins.

Since there will be a high speed of load variation, it is convenient touse load indicators of the recording type as'shown in Figure 7. Leads 36of the strain gauges, therefore, should lead to a strain analyzer 31 anda direct inking oscillograph 38 or oscilloscope or indicating meter. Itwill be noted that there is shown also -a pair of dummy strain gauges3!, which are also connected in a bridge circuit with the active gauges.These dummy strain gauges, of the same resistwill be approximatelythesame. Now,-in measuring the force of each load-imparting pin,impulses from the gauges, that is. changes in resistance, are picked upon an analyzer 31 (such as a brush amplifier and strain analyzer) andare recorded .at the direct inking oscillograph II. The oscillograph iscalibrated to record in pounds, and it provides a continuous record ofthe force component exerted on the test bearing along the center-line ofopposite cells. An alternative to the use of external dummy gauges ll.permissible only with load cells in pairs along an axis, is to connectthe indicator of the two load cells along one axis as active arms of thesame bridge circuit in a manner such that a combined signal will be theresultant force along that axis. This load phasing of the indicators ispossible with the brush amplifier and strain analyzer.

One method of measuring torque is by the use of a brake arm or torquearm 29 shown in Figures 2 and 4. The torque arm is connected to the testbearing holder as illustrated. It can be of any desired length and theforce at its free end can be easily measured, e. g., by spring balanceweights, etc. The weight multiplied by the length of the arm, that isthe distance to the shaft, gives the torque directly, for instance, ininch-pounds. "Another method of determining torque would be to securethe free end of torque arm 29 and attach a resistance strain gauge tosaid torque arm to measure stress. Alternatively. the resistance straingauge could be attached to a separate strain element link secured to theend of the torque arm. Three or more load-applying units acting againsta load ring at three or more points equidistant around the circumferenceof said load ring can be used to simulate a radial load on a testbearing. However, I prefer four loadapplying units'spaced apart aroundthe circumference of the load ring because this provides radial forcecomponents at right angles and calculations can be more easily made whena polar load is simulated. The force component is transmitted throughthe load-applying and load-imparting units and acts on the test bearingin the direction of the load-applying unit center line. Since the forcepattern from each load cell can be accurately recorded, it is onlynecessary to make adjustments in the hydraulic system and the oscillatorsystem to produce a desired pattern. These adjustments are made inoscillator speed, volume of the fluid system, cam profile and phasing.of the came with each other and with the test bearing shaft. Phasing isachieved by suitably gearing together the oscillator shafts and the testbearing shaft. This gearing can be altered for any particular pattern.Oscillator or load-producing piston movement will be a function of thecam profile which will be determined by 'a particular load pattern.Since the force on a,cas,sa4 I it is possible to produce a force patternon the bearing of sufficient loaded bearing in the direction of theload-applying unit. Variations and modifications will obviously occur tothose skilled in the art.

What I claim is:

1. A device for producing rotating and pulsating loads on test bearingsin the testing of lubricants, which comprises a test bearing adapted toreceive a rotatable shaft, 9. load-imparting ring around the outersurface of the test bearing. at least three hydraulically-operatedpressureapplying units located equidistantly around the circumference ofsaid load-imparting r and transmitting force components theretosimulating operating load, means for producing pressure oscillation insaid pressure-applying units at a base pressure level, eachhydraulically-operated pressure-applying unit being independent of theothers and coupled with said means for producing pressure oscillations,means for-varying the compression in the hydraulic system forestablishing a selected base pressure, and means for synchronizing thepressure oscillations with the speed of the revolving shaft.

2. A device for simulating rotating and pulsating loads on a bearing inthe testing of lubricants,

which comprises a test bearing adapted to re-- ceive a rotatable shaft,a load-imparting ring embracing said test bearing, at least threeloadapplying units located equidistantly around the circumference of theload-impartmg ring and capable of applying force against the ring, anequal number of hydraulic oscillator units, means for operating thehydraulic oscillator units in selected sequence at a selected basepressure level, a hydraulic pressure-transmitting system connecting eachoscillator unit to a load-applying unit, means for independently varyingthe compression in the system connecting each oscillator unit to arespective load-applying unit, and means for synchronizing the pressureoscillations with the speed of the rotating shaft.

3. A device'for simulating rotating and pulsating loads on bearings inthe testing of lubricants.

comprising a test bearing adapted to receive a rotatable shaft, a testbearing holder fitting around the outside surface of the test bearing,an inner race fitting around the outside surface of said test bearingholder, an outer race, needle rollers between said inner race and saidouter race, at least three load-imparting pins located equidistantiyaround the circumference of the outer race and capable of exertingradially "applied force against said outer race, a, load-applyinghydraulic piston capable of oscillating against each load-imparting pin,an equal number of hydraulic pressure-producing cylinders, a hy-vdraulic pressure-transmitting system connecting each hydraulicpressure-producing cylinder to a load-applying piston, cam means forproducing pressure oscillations within each pressure-producing cylinderin predetermined sequence, means for producing -momentary and cyclicincreases in base pressure in each hydraulic pressure transmittingssytem independently of the others, and means for time-phasing thepressure oscillations with the speed of the rotating shaft.

4. A device for simulating rotating and pulsating loads on bearings inthe testing of lubricants, comprising a test bearing, a shaft rotatablewithin the inner surface of the test bearing, a test bearing holderfitting around the outside of the intensity and frequency to" match theforce component of a dynamically test bearing, a load-imparting ringembracing the test bearing holder, an anti-friction bearing between andin close contact with said test bearing holder and said load-impartingring, a torque arm extending from said test bearing holder, meansassociated with said torque arm for measuring the force tending to causeits movement with shaft rotation, at least three load-applying unitslocated equidistantly around the circumference of the load-impartingring and capable of applying force against said load-imparting ring, anequal number of hydraulic oscillator units. means for operating the samein selective sequence at any base pressure level, a hydraulicpressure-transmitting system connecting each oscillator unit to aload-applying unit, means for independently varying the compression inthe hydraulic system connecting each oscillator unit to a respectiveload-applying unit, means for synchronizing the pressure oscillationswith the speed of the rotating shaft, and means for exhibiting strainsimposed upon the several load ap lying units.

5. A device for simulating rotating loads on bearings in the testing oflubricants, comprising a test bearin a rotatable shaft to revolve withinthe inner surface of the test bearing, a test bearing holder fittingaround the outside surface of the test bearing. an inner race fittingaround the outside surface of said test bearing holder, an outer race,needle rollers between said inner race and said outer race, a torque armextending from said test bearing holder, means associated with saidtorque arm for measuring torque in rotation of the shaft as transmittedto the test bearing, load-imparting pins located equidistantly aroundthe circumference of the outer race and capable of intermittentlyapplying pressure against said outer race, means associated with eachload-imparting pin for exhibiting strain, a load-applying hydraulicpiston in contact with each load-imparting pin, an equal number ofhydraulic pressure-producing cylinders, a hydraulicpressure-transmitting system connecting each hydraulicpressure-producing cylinder to one of said load-applying pistons, apiston within each pressure-producing cylinder for oscillating the fluidwithin said pressure-transmitting system, means for oscillating eachpressure-producing piston, means for varying the degree of fluidcompression in the system and means for timephasing'the pressureoscillations with the speed of the revolving shaft.

. 6. A bearing and lubricant testing machine comprising a test bearing.a shaft mounted to rotate within the test bearing, a test bearing holderfitting around the outside of the test bearing, a load-imparting ringembracing the test bearing holder, an anti-friction bearing between andin close contact with said test bearing holder and said load-impartingring, four load-imparting pins capable of oscillating against theoutside surface of said load-imparting ring in radial direction andlocated apart around the circumference of said load-imparting ring, aloadapplying piston positioned to be oscillated against eachload-imparting pin, an equal number of hydraulicpressure-producingcylinders, a fluidcontaining hydraulicload-transmitting line connecting each load-applying piston to a mainand an auxiliary prmsure-producing cylinder, a pressure-producing pistonwithin each pressure-producing cylinder for oscillating the fluid withinthe respective load-transmitting line communicating therewith and forimparting cyclic increases in base pressure in the individual loadtransmitting lines, a motor driven cam shaft. cams thereon presented toeach pressure-producing piston for oscillating said pistons inpredetermined sequence, whereby :by varying the cam profiles the degreeof fluid compression in the hydraulic system and the oscillation of eachloadapplying piston may be varied, means for coupling said motor to saidshaft for rotating the same with said cams and thereby synchronizing thepressure oscillations with the speed of the rotating shaft, means fordetermining the force which each load-imparting pin exerts upon the loadring, and means for determining torque.

7. A hearing and lubricant testing machine comprising a rotatable shaft,a test bearing in which said shaft is journalled, a test bearing holderfitting around the outside of the test bearing, an inner race ringfitting around the outside surface of said test bearing holder, an outerrace ring, needle rollers between said inner and outer race rings, aload-imparting ring fitting around the outside surface of said outerrace ring, four load-imparting pins capable of oscillating against theoutside surface of said loadimparting ring and located 90 apart aroundthe circumference of said load ring, a load-applying piston positionedto be oscillated against each load-imparting pin, an equal number ofhydraulic pressure-producing cylinders, a fluid-containing hydraulicload-transmitting line connecting each load-applying piston to apressure-producing cylinder, a pressure-producing piston within eachpressure-producing cylinder for oscillating the fluid within saidload-transmitting line, a motor driven shaft carrying cams which bearupon the several pressure-producing pistons for oscillating said pistonsin predetermined sequence, the variation of cam profiles thereby varyingthe degree of fluid compression in the hydraulic system and theoscillations of individual load-applying pistons, gearing for drivingsaid rotatable shaft from said motor driven shaft, thereby synchronizingthe oscillations of the load-applying pistons with the speed of therotating shaft, means for determining the force which each loadimpartingpin exerts upon the load ring, and means for determinin torque.

8. A bearing and lubricant testing machine comprising a test bearing. ashaft rotatable with in the test bearing, a test bearing holder fittingaround the outside of the test bearing, an inner race ring fittingaround the outside surface of said test bearing holder, an outer racering, needle rollers between said inner and outer race rings, aload-imparting ring fitting around the outside surface of said outerrace ring, four load-imparting pins capable of oscillating against theoutside surface of said load-imparting ring and located apart around thecircumference of said load ring, a load-applying piston positioned to beoscillated against each load-imparting pin in radial direction, an equalnumber of hydraulic pressure-producing cylinders, a fluid-containinghydraulic load-transmitting line connecting each load-applying piston toa main pressure-producing cylinder and an auxiliary pressure-producingcylinder, 9. pressure-producing piston within each pressure-producingcylinder for oscillating the fluid within said load-transmitting lineand for cyclically increasing base pressure in the respectiveload-transmitting line, a motor driven cam shaft, cams on said shaft foroscillating each pressure-producing piston, means for varying the volumeof the load-transmitting line thereby varying the degree of fluidcompression in the hydraulic system, gearing connecting the motor drivencam shaft with the rotatable shaft for time phasing the oscillations ofthe pressure producing pistons with the speed of the rotatable shaft.means for determining the force which each load-imparting pin exerts onthe load ring. and means for determining torque.

- REGINALD J. S. PIGO'I'I.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,563,941 Kasley Sept. 15, 19251,995,882 Boden Mar. 26, 1935 2,471,423 Glsser May 31, 1949 FOREIGNPATENTS Number Country Date 318,491 Germany Jan. 28, 1920 557,248 FranceApr. 30, 1923

